1. Field of the Invention
The present invention relates to a mounting structure for an oil level sight glass for visually observing an amount of oil held in a reservoir of an internal combustion engine. More particularly, the present invention relates to a crankcase having a mounting structure configured to receive engine oil level sight glass, and a retainer member for holding the oil level sight glass.
2. Description of the Background Art
A number of monitoring structures for an oil level sight glass for internal combustion engines of motorcycles are known. An example of a mounting structure for an oil level sight glass is disclosed in the Japanese patent document JP-A No. 2000-282837.
According to the Japanese patent document JP-A No. 2000-282837, the mounting structure for the oil level sight glass, for an engine of a motorcycle, includes a body which is attached to the engine. The body includes a communication chamber which communicates with an oil reservoir, and a sight glass portion which covers an end portion of the communication chamber. The body has scale marks provided at the periphery of its end portion to indicate the level of oil held in a reservoir of the internal combustion engine.
The body with the sight glass portion pre-fitted therein is mounted striding a crankcase and an oil pan of an internal combustion engine. The body is positioned abutting the crankcase and the oil pan such that an upper communication port and a lower communication port of the body are connected to a through hole formed in the crankcase and a communication hole of the oil pan, respectively. The oil level sight glass is attached to the engine by bolting two downwardly projectingly bolting parts formed on the body to the oil pan surface.
Generally, when a same type of internal combustion engine is commonly used for different types of motorcycles, the position in which the engine is mounted may differ between differently configured motorcycles. Particularly, in a case where an internal combustion engine is mounted transversally on a motorcycle with its crankshaft oriented in a vehicle width direction, the direction in which the cylinders of the engine protrude from the crankcase differs, and hence the position in which the engine is mounted may differ depending on the type of motorcycle.
When the position of mounting of an internal combustion engine changes, even though the oil level of the engine can be viewed through the oil level sight glass attached to the oil pan or the crankcase, the scale marks provided on the oil level sight glass for checking the oil level may not provide correct measure of oil level in the engine, and can no longer be used as a criterion to correctly measure the oil level in the engine.
In such a case, it is necessary to replace the scale marks of the oil level sight glass to correctly check the oil level in the engine. However, in the case of the oil level sight glass disclosed in the patent document JP-A No. 2000-282837, the scale marks provided on the body can not be replaced, when required. In such situations, a replacement of the body of the oil level sight glass with appropriate scale marks is required. Since the body has a sight glass portion pre-fitted therein, replacing the body makes it necessary to replace the sight glass portion, too. In other words, the oil level sight glass as disclosed in JP-A No. 2000-282837 may not be used when engines are mounted in different positions on different motorcycles.
Accordingly, an object of the present invention that has been made in view of the above situation is to provide a versatile mounting structure for an oil level sight glass for an internal combustion engine, the mounting structure allowing the oil level sight glass to be used commonly between internal combustion engines mounted in different positions on different motorcycles and also allowing appropriate scale marks to be easily provided.